The proposed research is designed to develop more effective self-change models and manuals for smoking cessation. Although smoking is the most preventable cause of cancer, 54 million Americans continue to smoke. Sixty percent of these smokers tried to quit but failed. Most smokers report that they would not attend formalized treatment programs but would use self-help materials. Unfortunately, available self-help treatment manuals have been as ineffective as formalized treatment programs. Consequently, there is an urgent need to develop and disseminate more effective models and manuals for individuals wishing to quit smoking on their own. The proposed research is a continuation of three years of research on self-change approaches to smoking cessation. These studies have enhanced a Transtheoretical Model which involves ten change processes receiving differential use during four stages of change: precontemplation; contemplation; action; and maintenance. Causal modeling would be applied to a two-year longitudinal data set of 950 smokers and former smokers. Structural analyses would test causal models of the change processes which determine progress between each stage of change. Three competing theories would also be tested: (1) Self-Efficacy Theory; (2) Decision Making Theory; and (3) A Cognitive-Behavioral Theory of Relapse. Profile analyses would assess paterns of change demonstrated during the two year period quitting smoking. The causal models and profile analyses would be used to develop self-help manuals for smokers at four different stages of change. Eight experiments would evaluate the transtheoretical manuals against two leading self-help manuals. The experiments would also assess the effects of expectations, adherence to the manual, homework assignments, length and cost of materials, graphics, reactivity of measures, and spouse and therapist contributions. Following two years of model and manual development, the self-help materials will be subjected to a field trial on a sample of 400 smokers. This research is designed to contribute to cancer control by providing more effective manuals for those wishing to quit smoking in a cost-efficient manner.